Triceratops
Triceratops is a genus of ceratopsian dinosaur from the Late Cretaceous Period of North America. It is one of the most well known of all dinosaurs. Description Triceratops was one of the largest ceratopsians, measuring up to 9 meters in length"Triceratops in The Natural History Museum's Dino Directory". Internt.nhm.ac.uk. Retrieved 2010-08-03. and perhaps 6 to 12 tonnes in weight.Alexander, R.M. (1985). "Mechanics of posture and gait of some large dinosaurs". Zoological Journal of the Linnean Society 83: 1–25. doi:10.1111/j.1096-3642.1985.tb00871.x. Its most distinctive feature was its skull, which was adorned with three horns and a frill. One horn was positioned above the nostrils, and the other two (which could reach lengths of a meter or more"Denver museum unveils 7-foot-long, 1,000-pound Triceratops skull". The Daily Courier. November 18, 2003. Retrieved 2013-12-26.) sat above the eyes. The frill of Triceratops was relatively short compared to other ceratopsians, and was also completely solid."Making A Triceratops .Science Supplies Missing Part! Of Skeleton". Boston Evening Transcript. October 24, 1901. Retrieved 2013-12-26. It was initially believed that the front limbs of Triceratops sprawled at an angle in order to bear the weight of its large head.Dodson, P. (1996). The Horned Dinosaurs. Princeton University Press, Princeton, New Jersey. ISBN 0-691-02882-6. However, recently discovered ceratopsian trackways and digital reconstructions of the animal show that all its legs were held upright with only slight flexion in the elbow region, which is a similar position to that of modern rhinoceroses.Fujiwara, S.-I. (2009). "A Reevaluation of the manus structure in Triceratops (Ceratopsia: Ceratopsidae)". Journal of Vertebrate Paleontology 29 (4): 1136–1147. doi:10.1671/039.029.0406. An as-yet undescribed specimen of Triceratops shows that its skin may have been covered in bristle-like structures, similar to its earlier relative Psittacosaurus.Perkins, S.; Csotonyi, Julius T. (2010). "Dressing Up Dinos". Science News 177 (3): 22–25. doi:10.1002/scin.5591770321. Classification Many early researchers classified Triceratops as a centrosaurine ceratopsian,Hatcher, J. B., Marsh, O. C., and Lull, R. S. (1907) The Ceratopsia. Government Printing Office, Washington, D.C. ISBN 0-405-12713-8. but several analyses since then have found it is better understood as a chasmosaurine.Lehman, T. M. (1990). The ceratopsian subfamily Chasmosaurinae: sexual dimorphism and systematics. in: Carpenter, K., and Currie, P. J. (eds.). Dinosaur Systematics: Perspectives and Approaches. Cambridge University Press, Cambridge, pp. 211–229. ISBN 0-521-36672-0. Two valid species are known, T. horridus and T. prorsus,Erickson, B.R. (1966). "Mounted skeleton of Triceratops prorsus in the Science Museum". Scientific Publications of the Science Museum 1: 1–16. although many others have been named. The below cladogram by Scott Sampson and colleagues in 2010 shows the position of Torosaurus among the ceratopsians:Scott D. Sampson, Mark A. Loewen, Andrew A. Farke, Eric M. Roberts, Catherine A. Forster, Joshua A. Smith, and Alan A. Titus (2010). "New Horned Dinosaurs from Utah Provide Evidence for Intracontinental Dinosaur Endimism". PLoS ONE. 5 5 (9): e12292. doi:10.1371/journal.pone.0012292. PMC 2929175. PMID 20877459. |2= |2= }} }} }} }} }} }} }} }} }} }} }} }} History A pair of brow horns belonging to Triceratops was discovered near Denver, Colorado in 1887. The paleontologist Othniel Charles Marsh believed that the horns were of Pliocene age, and classified the specimen as a bison, which he named Bison alticornis.Marsh, O.C. (1887). "Notice of new fossil mammals". American Journal of Science 34: 323–331. He found similar fossils the next year, describing them as part of the dinosaur genus Ceratops,Marsh, O.C. (1888). "A new family of horned Dinosauria, from the Cretaceous". American Journal of Science 36: 477–478. but still interpreted the original pair of brow horns to be from a bison. It was not until a more complete skull was found that Marsh recognized all the specimens to be of the same genus, which he named Triceratops in 1889.Marsh, O.C. (1889b). "Notice of gigantic horned Dinosauria from the Cretaceous". American Journal of Science 38: 173–175. John Scannella and Jack Horner proposed in 2010 that the closely related genus Torosaurus was actually the adult form of Triceratops.Scannella, J.; and Horner, J.R. (2010). "Torosaurus Marsh, 1891, is Triceratops Marsh, 1889 (Ceratopsidae: Chasmosaurinae): synonymy through ontogeny". Journal of Vertebrate Paleontology 30 (4): 1157–1168. doi:10.1080/02724634.2010.483632 . Their conclusions have not been universally accepted, however (see the [[Torosaurus#Ontogeny debate|corresponding section in the ''Torosaurus article]]).Longrich NR, Field DJ (2012) Torosaurus Is Not Triceratops: Ontogeny in Chasmosaurine Ceratopsids as a Case Study in Dinosaur Taxonomy. PLoS ONE 7(2): e32623. doi:10.1371/journal.pone.0032623 Paleobiology Social behavior Triceratops is often portrayed as a herding animal, although there is little direct evidence to support this. In fact, only one bonebed of the genus has been found, containing only three juveniles.Mathews, Joshua C.; Brusatte, Stephen L.; Williams, Scott A.; and Henderson, Michael D. (2009). "The first Triceratops bonebed and its implications for gregarious behavior". Journal of Vertebrate Paleontology 29 (1): 286–290. doi:10.1080/02724634.2009.10010382 . Diet Triceratops was herbivorous, and like other ceratopsians it had a large beak.Ostrom, J. H. (1966). "Functional morphology and evolution of the ceratopsian dinosaurs". Evolution 20 (3): 290–308. doi:10.2307/2406631 . JSTOR 2406631. It had especially large batteries of teeth, and at any time a single animal may have had up to 800 teeth in its mouth (although only a small fraction was in use at any given time due to tooth replacement).Dodson, P.; Forster, C.A.; and Sampson, S.D. (2004) Ceratopsidae. In: Weishampel, D. B.; Dodson, P.; and Osmólska, H. (eds.), The Dinosauria (second edition). University of California Press, Berkeley, pp. 494–513. ISBN 0-520-24209-2. Due to the position and structure of its skull and teeth, Triceratops likely ate low-growing, fibrous plants. Horns and frill function The horns and frill of Triceratops were traditionally thought to have been used in self-defense. Although this is a feasible use for these structures (and one perhaps supported by fossil evidence),Farke, A. A. (2004). "Horn Use in Triceratops (Dinosauria: Ceratopsidae): Testing Behavioral Hypotheses Using Scale Models" (PDF). Palaeo-electronica 7 (1): 1–10. Retrieved 20 November 2010. more recent studies have shown that their primary use was likely for display.Davitashvili, L. Sh. (1961). Teoriya Polovogo Otbora (Theory of Sexual Selection). Izdatel'stvo Akademii nauk SSSR. p. 538. Modern animals with similar structures use them for this purpose, and the wide range of ceratopsian adornments make each species highly distinctive from each other.Farlow, J.O. and Dodson, P. (1975). "The behavioral significance of frill and horn morphology in ceratopsian dinosaurs". Evolution 29 (2): 353. doi:10.2307/2407222 . JSTOR 2407222. In popular culture Triceratops is one of the most famous dinosaurs due to its distinctive appearance, and is often depicted in combat with Tyrannosaurus, which was a contemporary predator in the area. It has appeared in a multitude of books, movies, television shows, and other media. Triceratops is also the state fossil of South DakotaState of South Dakota. "Signs and Symbols of South Dakota.....". Retrieved 2007-01-20. and the state dinosaur of Wyoming.State of Wyoming. "State of Wyoming – General Information". Archived from the original on February 10, 2007. Retrieved 2007-01-20. References Category:Animals Category:Dinosaurs Category:Herbivores Category:Ceratopsians Category:Fossil taxa described in 1889